I have this code:
    class a(){
      function b(){
         if(isset($this){
            echo 'instance! ';
            echo get_class($this);
         }else{
            echo 'static';
         }
      }
    }
class C{
  public function test(){
      a::b();
  }
}
$CC=new C;
$CC->test();
This will echo
instance C
 
    